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Net-Zero Home Experiment

Net-Zero Home Experiment
Traditional styling hides state-of-the-art energy conservation f
Building a net-zero home – a house that produces all the energy it needs – is a delicate balance, to be sure. It’s one that starts with designing a home that consumes as little energy as possible, given that the systems used to produce energy – solar panels, solar hot water heaters, and geothermal piping – add expense. And steps taken to reduce energy consumption -- reducing fenestration or creating an airtight shell come immediately to mind -- can’t interfere with the home’s aesthetic qualities or livability.
That’s the challenge Brookfield Homes faced with its Pure Blue net-zero demonstration home built earlier this year in the Virginia suburbs of Washington D.C.  The public builder raised the ante by trying to make the 4,000-square-foot prototype fit on standard subdivision lot in a conventional master plan community.

The experiment succeeds from a technical standpoint. But it’s doomed by shortcomings in the livability of its floor plan, created by the drive to save energy.

The Craftsman/Colonial-style home, with its inviting front porch and stone foundation, certainly looks right at home in the Avendale neighborhood of production homes. A large solar array, invisible from the street in front of the home, sits on a gabled roof with a pitch designed to capture solar power as efficiently as possible. Its high location also removes it from the threat of shadows cast by neighboring homes.

To its credit, Brookfield employed passive solar techniques too often ignored by developers. Strategically placed low-e, triple-pane windows capture daylight when needed. Shallow roof overhangs on the first and second floors block direct sunlight during the hottest summer months. The tactics help the home achieve a HERS (Home Energy Rating System) score of -1.

A simple rectangular form with minimal bump-outs provide construction savings to pay for energy upgrades. Structural insulated panels (SIPS) – two pieces of OSB that sandwich six inches of foam insulation – form the exterior walls. They are wrapped in a reflective low-e housewrap to reduce heat gain then taped to resist air penetration.

Controlling unwanted air leaks is a key to energy-efficient construction. Brookfield employed a heat-recovery ventilator to pump fresh air into the house. And low-VOC paints and furnishings were used throughout to reduce the potential for indoor air pollution.

The downside to SIPs is that wiring, piping, and ducting typically need to be run between the panels and drywall. Also, the location of windows, doors, and other penetrations must be decided upfront. Making changes during construction can add cost and complexity.

The home includes a package of products to reduce electricity needs, including LED lighting throughout the house. It also used a high-efficiency, 90-percent efficient, HVAC system, Energy-star rated appliances, and a hybrid hot water heater that operates like a heat pump. It eschewed a geothermal system because of high upfront costs.
Unlike the other models in the community, which include formal living and dining rooms, Pure Blue is done with an open floor plan, featuring a large central space with nine-foot ceilings.

Contemporary touches in the home include floating vanities, see-through fireplaces, and Euro-style cabinets.

The look is compromised by a series of random traditional details -- raised panel interior doors, box beams on a bedroom ceiling, and brick veneer. Faux brick is used to nice effect in the great room. It seems like overkill when it reappears along an interior wall in the finished basement. The home includes several sustainable design touches that would appeal to net-zero home buyers. Sleek Eco Veneer cabinets in the 

kitchen are made with sustainable bamboo. A countertop was repurposed from a black walnut tree removed during development.

Brookfield fought hard to gain local government approval to install a greywater system rarely seen in East Coast subdivisions. The system collects rainwater from downspouts in tanks under the deck in the back of the home. The same tanks store filtered water from bathroom sinks, showers, and the washing machine.

The big problem with Pure Blue is that the first floor living space isn’t very bright, the result of the effort to limit solar gain. Small windows that run high along the  great room walls create a dimly limit main living area, even on the sunny day when I visited. Watching television in the long great room wouldn’t be a comfortable experience either.

Brookfield has no plans to offer Pure Blue as a standard model, which is probably a good thing considering the flaw in the floor plan. Its goal was to experiment with and test new technology with the goal of incorporating the best of what it finds in other production models. The day I visited salespeople tried to steer me into buying one of several other models in the community.

Despite the home’s design shortcoming, and the builder’s limited intentions, Brookfield is to be commended for its effort to experiment with net-zero housing. It plans to gather data on the home’s performance and compare it to the performance of the home next door. The company, traditionally publicity shy, even created a microsite devoted to Pure Blue, complete with videos, pictures, and an interactive floor plan. It’s worth checking out at: 
(All images in this post courtesy Brookfield Homes)

Boyce Thompson is the former Editorial Director of Builder Magazine, and the author of The New New Home.

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